Ceiling-mounted robots are also known in the art, as for example from German patent publication 102008 013 729, published on 17 Sep. 2009. The objective is to allow the robotic arm to access and work within a large range while allowing mobility in the free space above objects within the work area.
Cable robots have been proposed in the academic and patent literature but are not in widespread use in industry. A cable robot is a robot or robotic platform that is held in space using cables so that the robot can be moved throughout a relatively large space or volume in comparison with articulated arm robots. To provide stability, most cable robot systems have cables that support the weight of the robotic platform from above as well as cables that stabilize the platform from below. An example is described in U.S. Pat. No. 7,753,642. While the stability can be satisfactory, the encumbrance of the lower stabilizing cables defeats the advantages of the mobility of a cable robot.
Cable robots that are suspended from cables only are also known in the paper titled “On the Design of a Three-DOF Cable-Suspended Parallel Robot Based on a Parallelogram Arrangement of the Cables” by Dinh-Son Vu, Eric Barnett, Anne-Marie Zaccarin, and Clément Gosselin and published in Springer International Publishing AG 2018 (C. Gosselin et al. (eds.), Cable-Driven Parallel Robots, Mechanisms and Machine Science 53), a cable robot is described to use 3 pairs of cables configured as parallelograms to have the capability of moving in a 3D environment maintaining a constant orientation of the central module from a top view (z axis). The main motivation of the work is to reduce the number of actuators needed in a translational parallel cable-suspended robot while ensuring a large workspace. One of the applications of such a mechanism is large-scale 3D printing, which typically requires positioning an end-effector with a constant orientation. This concept does not provide practical stability for an end-effector that would apply torque to the robot.
In U.S. Pat. No. 6,809,495, a camera platform is suspended by four cables, with the platform being stabilized by gravity as it hangs from the platform.
For a robot, stability is important because the end effector of the robot can exert force as it performs its tasks. The prior art suspended cable robots are limited in their ability to stabilize the robot end effector without having cables pulling downward.